<?php if (!defined('FIT_PATH')) exit('No direct script access allowed');
/**
 * @copyright 2009 - 2011 Bincent.com. All Rights Reserved.
 * @license http://www.apache.org/licenses/LICENSE-2.0
 * @package FitPHP
 * @subpackage helper
 * 
 * @author Hongbin Hsu <hongbin.hsu@gmail.com> Initial.
 * @version $Id: helper/string.php 1.0 2009-07-18 13:34 hongbin.hsu $
 */

// ------------------------------------------------------------------------
/**
 * 截取字符串
 * 
 * @param string $string 待截取字符串
 * @param int $length 保留长度
 * @param string $dot 后缀符号
 * @param string $charset 字符集
 * @return string
 */
if (!function_exists('cut_str'))
{
	function cut_str($string, $length, $dot = '...', $charset = 'utf-8')
	{
		if(strlen($string) <= $length) { return $string;}
	
		$string = str_replace(array('&amp;', '&quot;', '&lt;', '&gt;'), array('&', '"', '<', '>'), $string);
	
		$strcut = '';
		if(strtolower($charset) == 'utf-8') {
			$n = $tn = $noc = 0;
			while($n < strlen($string)) {
				$t = ord($string[$n]);
				if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {
					$tn = 1; $n++; $noc++;
				} elseif(194 <= $t && $t <= 223) {
					$tn = 2; $n += 2; $noc += 2;
				} elseif(224 <= $t && $t < 239) {
					$tn = 3; $n += 3; $noc += 2;
				} elseif(240 <= $t && $t <= 247) {
					$tn = 4; $n += 4; $noc += 2;
				} elseif(248 <= $t && $t <= 251) {
					$tn = 5; $n += 5; $noc += 2;
				} elseif($t == 252 || $t == 253) {
					$tn = 6; $n += 6; $noc += 2;
				} else {
					$n++;
				}
	
				if($noc >= $length) { break; }
	
			}
			if($noc > $length) { $n -= $tn; }
			$strcut = substr($string, 0, $n);
		} else {
			for($i = 0; $i < $length; $i++) {
				$strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];
			}
		}
		$strcut = str_replace(array('&', '"', '<', '>'), array('&amp;', '&quot;', '&lt;', '&gt;'), $strcut);
	
		return $strcut.$dot;
	}
}